--- a/data/json/items/ammo/40x46mm.json
+++ b/data/json/items/ammo/40x46mm.json
@@ -3,6 +3,7 @@
     "abstract": "40x46mm_grenade",
     "type": "AMMO",
     "name": { "str": "40x46mm grenade" },
+    "volume": "129 ml",
     "price": 10000,
     "price_postapoc": 6000,
     "flags": [ "IRREPLACEABLE_CONSUMABLE" ],
--- a/data/json/items/ammo/40x53mm.json
+++ b/data/json/items/ammo/40x53mm.json
@@ -3,6 +3,7 @@
     "abstract": "40x53mm_grenade",
     "type": "AMMO",
     "name": { "str": "40x53mm grenade" },
+    "volume": "137 ml",
     "price": 10000,
     "price_postapoc": 6000,
     "flags": [ "IRREPLACEABLE_CONSUMABLE" ],